High velocity projectile



Nov. 27, 1945. G. R. ERICSON HIGH VELOCITY PROJECTILE Filed Aug. 26,1941 N w mm NR R W m Rgm E t G y R A m M G G 1 H Patented Nov. 27, 1945res 'E'E'i' FFHE This invention relates to projectiles and particularlyto projectiles intended to be fired at high velocities.

As is well known to those skilled in the art, the

exterior ballistic efiiciency of a high velocity pro-,

jectile depends to a great extent on a high ratio of projectile weightto cross-sectional area while the internal ballistic eificiency of theprojectile depends on a high ratio of cross-sectional area to projectileweight. That is to say, the require-.

ments for internal and external ballistic efficiency are just theopposite.

In order to avoid the above mentioned difficulty it has been proposed touse a projectile having comparatively great length and comparativelysmall diameter but provided with a packing, plug or sabot to increasethe cross-sectional area of the projectile so that it will fit into agun of comparatively large diameter, the sabot being of comparativelylight weight and detachable as soon as up to the present applicant doesnot know that: i

any sabot has been developed having the necessary characteristics whichmay be summarized as follows: First, it must form a positive andeffective seal against leakage of gas around (or through) the projectileduring the discharge of the gun; second, it must firmly engage theprojectile and also the rifling of the gun during discharge through thebarrel so as to give the projectile the proper spin; third, it mustmaintain the projectile co-aXial with the barrel and guide it so thatthe centrifugal force due to the spin of the projectile will not initself cause undue precession or yaw of the projectile in flight;fourth, it must be promptly detached from the projectile as soon as itleaves the gun; fifth, it must be of comparatively light weight; sixth,the projectile itself must have a high ballistic coefficient whendetached from the sabot.

I obtain the desirable results outlined above by the construction shownin the accompanying drawing and described in the following specificationand claims.

Referring to the drawing:

Fig. 1 shows a complete round of ammunition embodying my improved sabotand projectile, parts being shown in section,

Fig. 2 shows the base of the assembled projectile and sabot detachedfrom the cartridge case,

Fig. 3 shows the condition and relation of the projectile and sabotwhile traveling through the barrel of the gun,

Fig. 4 shows a slightly modified form of sabot and projectile,

Fig. 5 shows the condition of the device shown in Fig. 4 while travelingthrough the barrel of the gun; and

Fig. 6 shows the adaptation of certain features of the invention to anozzle type projectile.

The reference numeral l indicates the projectile having an ogee shape atthe front end terminating in a shoulder 2 which is shown somewhatexaggerated in the drawing for purpose of illustration. At the rear ofthe shoulder cylindrical portion 3 followed by a boat tail or conicalportion 4. The projectile may be made of whatever material desired andmay or may not carry an explosive charge and fuse.

The sabot 5 comprises a tubular central portion having a comparativelythin inturned front flange G separated by an annular groove 1 from athicker inturned flange 8. The inside diameter of the forward flange 6is such as to snugly fit the short cylindrical portion 3 of theprojectile while the internal diameter of the flange 8 is of a slightlylarger diameter so that it can not stick or wedge onto the projectile.The difference in internal diameter between the members 6 and 1 may becomparatively small especially in small projectiles. Fifteen or twentythousandths of an inch difference is ample for a projectile in the orderof .50 caliber. At the rear of the sabot openings 9 are provided for apurpose which will be hereinafter described. These openings are formedbetween prongs I 0 terminating in guide members H engaging the rear ofthe projectile to maintain the projectile in position coaxial with thebarrel of the gun. The outside diameter of the prongs I0 is preferably afreely sliding fit on the lands of the rifling of the gun, the numberand width of the prongs i0 is such that they cannot expand into therifling grooves but will bridge the grooves.

The turning action is provided by a turning band l2 of soft materialsuch as gliding metal which is adapted to be engraved by the rifling inthe usual manner.

The projectile and sabot may be applied to cartridge case 4 as indicatedin Fig. 1.

In operation the explosion of the propelling in Fig. 3 but also to holdthis flange in rigid.

frictional driving relation with the projectile so as to transmit thenecessary spin to the bullet. The shoulder 2 may be narrowed so as todig into the softer metal of the sabot to cause a more positive drivingengagement but this is not ordinarily necessary.

When the projectile reaches the end of the gun barrel the openings 9permit the escap of gas from the gun before the prongs I of the sabotare clear of the gun barrel. In this manner the disturbing force of themuzzle blast is reduced before the projectile is free to be tippedsideways and the likelihood of a substantial amount of yaw being set upat the instant of discharge is greatly reduced.

As soon as the prongs H) are free from the gun barrel centrifugal forceSprings the members In and l I outwardly vary slightly but still enoughto insure frictional disengagement from the projectile. It will be notedthat the deformation of the forward flange 6 to the position shown inFig. 3 will necessarily have the effect of expanding the internaldiameter of this member and forcibly cracking it away from theprojectile portion of the projectile 3. The deformation of the annularportion of the sealing member .tends to cause the prongs ID to springoutwardly so that as soon as they are free from the gun barrel they alsorelease the projectile. The elimination of the pressure in the gunbarrel permits the whole sabot to fall back in response to airresistance so that it drops free from the projectile a few yards afterit leaves-the gun barrel. The sabot being made of very lightconstruction does not travel far and falls to. the ground.

In the form of the invention shown in Fig. 4 the annular groove 8 inFig. 1 is not formed in the sabot but the limitation of deformation ofthe sabot I is accomplished by contact of the sabot with the shoulderI6, it being noted that the bending of the sabot'to the position shownin Fig. 5 causes expansion of the internal diameter of the sabot todisengage it from cylindrical surface 3 and the taper of the shoulder I6is much too steep to permit sticking of the sabot on this shoulder.

In the form of the invention shown in Fig. 6 the outside of theprojectile is cylindrical and the inside of the forward end is taperedinwardly with an ogee curve, the radius of which is preferably fromfourteen to twenty times the thickness of the wall at the rear end ofthe taper. The annular sealing surface 3 is formed behind the shoulderat the rear of the ogee forms the same as with the projectile shown inFig. 1. At the rear of the cylindrical portion 3 the projectile istapered out to the rear end with a curved taper. The equation of thecurve may readily be calculated as follows: The sound wave thrown offfrom the nose of the projectile striking the inner surface of the rearcone at any point should be reflected within a direction directlyopposite to the line of flight.

I claim:

1. In combination, a projectile for use in a gun, said projectileincluding a shoulder, a sabot having portions engaging the barrel ofsaid gun and said projectile including spaced annular flanges, at leastone of which is in sealing engagement with said projectile rearward ofsaid shoulder, the flange having sealing engagement with said projectilincluding an area capable of distortion under discharge pressure in saidgun to weaken said sealing engagement, whereby said sabot and projectilemay separate after discharge.

2. In combination, a projectile for use in a gun, said projectileincluding a shoulder, a sabot having portions engaging the barrel ofsaid gun and said projectile including spaced annular flanges, at leastone of which is in sealing engagement with said projectile rearward ofsaid shoulder, the flange having sealing engagement with said projectileincluding an area capable of distortion under discharge pressure in saidgun to weaken said sealing. engagement, whereby said sabot andprojectile may separate after discharge, and means including a spacedannular flange for limiting the distortion of an adjacent flange.

GEORGE R. ERICSON.

